Dry coil servo valve



Dec. 7, 1965 J D. BUCHANAN DRY con.. sERvo VALVE Filed April 12, 1957 Il J- J l i L INVENTOR.

J D BU CHANAN United States Patent O 3,221,760 DRY C011.. SERV@ VALVE J.D. Buchanan, Burbank, Caiif., assigner, by mesne assignments, to BellAerospace Corporation, Buffalo, NSY., a corporation of Delaware FiledApr. 12, 1957, Ser. No. 652,489 2 Claims. (Cl. 137-82) This inventionrelates in general to servo mechanisms, and in particular toelectro-hydraulic servo valves, such as shown in copending application,Serial No. 511,088 tiled May 25, 1955, by Martin P Wolpin et al.Furthermore, this invention comprises improvements over mechanisms asshown for example in U.S. Patents 2,655,939; 2,655,940; 2,625,136;2,767,689; and British Patent 712,- 329 of 1954.

An object of the present invention is to provide a valve of theaforesaid type in which the electrical parts of the valve are sealed oitin improved manner from the iluid containing chambers thereof.

Another object of the invention is to provide an improved valve asaforesaid which may be economically made by standard type productionmethods.

Another object is to provide a valve as aforesaid having relatively fewparts.

Other objects and advantages of the invention will be apparent from thefollowing specification wherein one form of the invention is shown inthe accompanying drawings, of which:

FIG. 1 is a vertical sectional view, partly in diagram, of one form ofthe device of the invention; and

FIG. 2 is a sectional view taken on line II-ll of FIG. 1.

As shown in the drawing, one form of the device of the invention may beemployed in conjunction with an hydraulic valve mechanism shown tocomprise a body having therewithin a valve spool 25 and oil passageways(not shown) as disclosed for example in FIG l of copending U.S. patentapplication Serial No. 511,088 led May 25, 1955 by Martin P. Wolpin etal.; the uid passageways exiting from the valve body 15 as indicated at16, 18, 20, 22, 30, 32 and 34. As in the prior application referred to,an actuator comprising cylinder 24, piston 26, and connecting rod 28, orthe like, may be loperatively coupled to the fluid conduits 20, 22 sothat the latter open into the cylinder 24 at opposite sides of thepiston. The port 16 constitutes the pressured fluid inlet of the valvemechanism, while the port 18 constitutes the return line; and thus itwill be understood that shifting of the valve spool 25 within the body15, as controlled by the electro-magnetic component of the device aswill be explained hereinafter, will cause the actuator 28 to bedisplaced in accord with the purpose of the mechainsm.

As in the case of the copending patent application, the fluidpassageways 30, 32 normally supply oil under equal pressures fromchambers at opposite ends of the valve spool 25, to correspondingopposed nozzles 40, 42 mounted as in a body block 44 and arranged to jetoil against opposite sides of a iiattened end portion 46 of the armature50 of the electromagnetic component of the device. The armature endportion 46 is disposed within an oil chamber 52 formed in body block 44,and chamber 52 communicates with port 34 which leads to the oil returnconduit 18. The armature end portion 46 is normally centered between thenozzles 40, 42 and is slightly spaced equally in relation therefrom,whereby constant flows of oil may pass through the nozzles 40, 42 fromthe chambers at opposite ends of the valve spool against the armaturepart 46 and thence through the return ZZW Patented Dec. 7, 1965 ICeconduit. However, any displacement of the armature part relative to thenozzles 40, 42 will differentially throttle the latter, and therebyupset the previous pressureequilibrium at opposite ends of the valvespool 25. This Will cause the Valve spool to shift with consequentadjustment of the valve action controlling ow of oil from the inlet 16through actuator ports 20, 22; thereby energizing the actuator 28consonant with the degree of deiiection of the armature part 46 from itsnormal centralized position.

To provide for such operation of the armature it is resiliently mountedrelative to the body portion 44, and as shown in FIG. l such resilientmounting may be arranged by providing the valve body portion to beinteriorly bored to receive in slip-fitted relation a sleeve mounting influid-sealed relation a spring metal tube 102 which extends upwardlytherefrom into fluid-sealed telescopically-titted relation within abored portion of the armature part 50. A lower stem portion 104 of thearmature is force-tted at its upper end into the tubearmature assembly.The armature part 104 tapers down to the nozzle control iiat end 46thereof, and thus it will be seen that the armature unit is supported onthe body member by means of the spring tube 102 which fluid-seals thenozzle chamber from the coil chamber and biases the armature towardcentral position relative to the nozzles while controlling oscillationmovements of the armature for differential throttling of the nozzles inresponse to signals to the coi-ls, as explained hereinafter. An O ring106 may be used to fluid seal the sleeve 100 to the body 44 and athreaded nut 108 holds the sleeve 100 in assembled position.

To cause the armature to rock upon the tube 102 as its fulcrum,electro-magnet coils 68, 70 are mounted within an enclosing housing 72at opposite sides of the armature, and are arranged to be differentiallyenergized in response to any control or error or other input signal, asis well understood in the art. Permanent magnets as indicated at 74, 76may also be employed at opposite sides of the armature for normallybiasing the armature to centralized position. Thus, rocking of thearmature for differential throttling of the nozzles 40, 42 will beaccompished in response to a signal and to a degree commensurate withthe strength of the signal to the coils 68, 70, as they may overcome thebalanced forces of the permanent magnets and as controlled by the springrate of the resilient housing 102. Thus, the tube 102 functionssimultaneously to normally spring-bias the armature towardsnozzle-centered position and controls oscillations thereof and returnsit to central position upon lapse of any biasing signal; while at thesame .time it iiuid seals the coils 68, '70 from contamination by oilfrom the nozzle chamber of the mechanism.

What is claimed is:

1. A pilot valve for a servo valve mechanism including a body, saidpilot valve comprising a flexible tube carried by said body inHuid-sealed relation therewith, two oppositely directed fluid-pressurenozzles carried by said body, an oscillating armature unit carried bysaid tube, said armature unit being formed with a paddle portion mountedin said tube in iiuid sealed relation therewith and extending betweensaid nozzles, said unit being also formed with an outwardly extendinglever portion on the side of said tube opposite said nozzles, said leverportion having abore receiving said tube in fluid sealed relationtherewith, and motor means for causing the lever portion to beselectively biased to rock said paddle portion into variably throttlingrelation with said nozzle, said tube serving to center said paddleportion and control rocking thereof and serving as a fluid seal betweensaid nozzles and said motor means.

2. A pilot valve having a body, said body having a bore therein, asleeve tted in said body bore, a flexible tube mounted adjacent one endin said sleeve in uid-sealed relation therewith, two oppositely directednozzles disposed Within said body, an oscillating llapper unit carriedby said tubel adjacent the other end thereof and comprising a taperedflapper portion mounted at one end Within said tube in uid-sealedrelation therewith, said flapper portion extending through said tube infree flapping relation therein and having its other end disposed betweensaid nozzles, said unit also having an oppositely extending armatureportion having a bore receiving said other end of said tube inuid-sealed relation therewith, and magnet means for biasing saidarmature portion and causing the apper unit to be selectively drawn intovariable throttling relation with said nozzles, said tube serving tocenter said flapper portion between said nozzles and control oscillationthereof while serving as a uid seal between said nozzles and said magnetmeans.

4 References Cited by the Examiner UNITED STATES PATENTS 1,173,0382/1916 Roschanek 74-18.1 X 1,827,560 10/1931 Binckley. 2,299,179 10/1942Rosenberger 74-18.1 2,599,159 6/1952 Breedlove 137-85 2,658,392 11/1953Vannah 137-85 X 2,767,689 10/1956 Moog 137-82 X 2,824,574 2/1958 Place137-623 10 2,835,265 5/1958 Brandstadr 137-82 OTHER REFERENCES MoogPublication: Control Engineering, May 1955,

McGraw-Hill, page 21.

ISADOR WEIL, Primary Examiner.

KARL I. ALBRECHT, RALPH H. BRAUNER, ALAN COHAN, Examiners`

1. A PILOT VALVE FOR A SERVO VALVE MECHANISM INCLUDING A BODY, SAIDPILOT VALVE COMPRISING A FLEXIBLE TUBE CARRIED BY SAID BODY INFLUID-SEALED RELATION THEREWITH, TWO OPPOSITELY DIRECTED FLUID-PRESSURENOZZLES CARRIED BY SAID BODY, AN OSCILLATING ARMATURE UNIT CARRIED BYSAID TUBE, SAID ARMATURE UNIT BEING FORMED WITH A PADDLE PORTION MOUNTEDIN SAID TUBE IN FLUID SEALED RELATION THEREWITH AND EXTENDING BETWEENSAID NOZZLES, SAID UNIT BEING ALSAO FORMED WITH AN OUTWARDLY EXTENDINGLEVER PORTION ON THE SIDE OF SAID TUBE OPPOSITE SAID NOZZLES, SAID LEVERPORTION HAVING A BORE RECEIVING SAID TUBE IN FLUID SEALED RELATIONTHEREWITH, AND MOTOR MEANS FOR CAUSING THE LEVER PORTION TO BESELECTIVELY BIASED TO ROCK SAID PADDLE PORTION INTO VARIABLY THROTTLINGRELATION WITH SAID NOZZLE, SAID TUBE SERVING TO CENTER SAID PADDLEPORTION AND CONTROL ROCKING THEREOF AND SERVING AS A FLUID SEAL BETWEENSAID NOZZLES AND SAID MOTOR MEANS.